Hello,

This patch modifies^D^D^D^Dsimplifies the frame code so that there is an 
extra frame below the innermost frame.  That extra frame maps any 
request for a register onto the regcache.

The thing to notice with this patch is how it eliminates the need to 
special case a level zero frame when fetching a frame's register. 
Instead, a register can be fetched using the recursive frame_register() 
method.

I'll look to commit this in a few days.

Follow on patches include:
- convert d10v to the current frame unwind mechanims
- deprecate methods such as POP_FRAME.

Andrew